U.S. patent number 6,903,045 [Application Number 09/884,775] was granted by the patent office on 2005-06-07 for tin promoted platinum catalyst for carbonylation of lower alkyl alcohols.
This patent grant is currently assigned to Eastman Chemical Company. Invention is credited to Donald Lee Carver, Andy Hugh Singleton, Gerald Charles Tustin, Joseph Robert Zoeller.
United States Patent |
6,903,045 |
Zoeller , et al. |
June 7, 2005 |
**Please see images for:
( Certificate of Correction ) ** |
Tin promoted platinum catalyst for carbonylation of lower alkyl
alcohols
Abstract
A carbonylation catalyst useful for producing esters and
carboxylic acids in a vapor phase carbonylation process, wherein
the catalyst includes a solid component having a catalytically
effective amount of platinum and tin associated with a solid
catalyst support material and a vaporous halide promoter
component.
Inventors: |
Zoeller; Joseph Robert
(Kingsport, TN), Singleton; Andy Hugh (Kingsport, TN),
Tustin; Gerald Charles (Kingsport, TN), Carver; Donald
Lee (Church Hill, TN) |
Assignee: |
Eastman Chemical Company
(Kingsport, TN)
|
Family
ID: |
25385366 |
Appl.
No.: |
09/884,775 |
Filed: |
June 19, 2001 |
Current U.S.
Class: |
502/169; 502/152;
502/154; 502/170; 502/181; 502/185; 502/227; 502/230 |
Current CPC
Class: |
B01J
23/626 (20130101); C07C 51/12 (20130101); C07C
67/36 (20130101); C07C 51/12 (20130101); C07C
53/08 (20130101); C07C 67/36 (20130101); C07C
69/14 (20130101); B01J 21/18 (20130101); B01J
37/0205 (20130101) |
Current International
Class: |
B01J
23/54 (20060101); B01J 23/62 (20060101); C07C
51/12 (20060101); C07C 51/10 (20060101); C07C
67/00 (20060101); C07C 67/36 (20060101); B01J
21/18 (20060101); B01J 21/00 (20060101); B01J
37/00 (20060101); B01J 37/02 (20060101); B01J
031/08 (); B01J 021/18 (); B01J 023/02 (); B01J
027/135 (); B01J 027/13 () |
Field of
Search: |
;502/152,154,169,170,181,185,227,230 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 120 631 |
|
Oct 1984 |
|
EP |
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0 759 419 |
|
Feb 1997 |
|
EP |
|
Other References
P Gelin, C. Naccache, and Y. Taarit, "Coordination Chemistry of
Rhodium and Iridium in Constrained Zeolite Cavities: Methanol
Carbonylation," Pure & Appl. Chem., vol. 60, No. 8, (1988) p.
1315-1320, Great Britian. .
H. Yagita, K. Omata, H. Tominaga and K. Fujimoto, "Vapor-phase
Carbonylation of Methanol Over Lead on Active Carbon Catalyst,"
Catalysis Letters, 2 (1989) p. 145-148, Germany. .
H. Yagita and K. Fujimoto, "Redox Cycle of Metal-on-Active Carbon
Catalyst in the Vapor Phase Carbonylation of Methanol," Journal of
Molecular Catalyst, 69 (1991) p. 191-197, Netherlands. .
K. Fujimoto, S. Bischoff, K. Omata and H. Yagita, "Hydrogen Effects
on Nickel-Catalyzed Vapor-Phase Methanol Carbonylation," Journal of
Catalysis, 133 (1992) p. 370-382. .
M. J. Howard, M. D. Jones, M. S. Roberts and S. A. Taylor, "C.sub.1
to Acetyls: Catalysis and Process," Catalysis Today, 18 (1993) p.
325-354, Amsterdam. .
T. Liu and S. Chiu, "Promoting Effect of Tin on Ni/C Catalyst for
Methanol Carbonylation," Ind. Eng. Chem. Res., 33 (1994) p.
488-492, USA. .
A. Krzywicki and M. Marczewski, "Formation and Evolution of the
Active Site for Methanol Carbonylation on Oxide Catalysts
Containing RhCl.sub.3," Journal of Molecular Catalysis, 6 (1979) p.
431-440, Netherlands. .
K. Fujimoto, H. Mazaki, K. Omata and H. Tominaga, "Promotion Effect
of Hydrogen on Vapor Phase Carbonylation of Methanol Over Nickel on
Active Carbon Catalyst," Chemistry Letters, (1987) p. 895-898,
Japan. .
H. E. Maneck, D. Gutschick, I. Burkhardt, B. Luecke, H. Miessner,
and U. Wolf, "Heterogeneous Carbonylation of Methanol on Rhodium
Introduced Into Faujasite-Type Zeolites," Catalysis Today, 3 (1988)
p. 421-429, Netherlands..
|
Primary Examiner: Bell; Mark L.
Assistant Examiner: Pasterczyk; J.
Attorney, Agent or Firm: Graves, Jr.; Bernard J.
Claims
What is claimed is:
1. A carbonylation catalyst comprising a solid component comprising
a catalytically effective amount of a platinum compound and a tin
compound associated with a solid catalyst support material and a
vaporous component comprising a catalytically effective amount of a
halogen promoter, wherein said platinum and tin compounds have a
valency greater than zero.
2. The carbonylation catalyst according to claim 1 wherein said
solid support is carbon.
3. The carbonylation catalyst of claim 2 wherein said carbon
support is activated carbon.
4. The carbonylation catalyst of claim 1 wherein said solid
includes from about 0.1 weight percent to about 10 weight percent
each of said platinum and tin compounds, as metals, and said weight
percents are based on the total weight of the solid component.
5. The carbonylation catalyst of claim 1 wherein said solid
component includes from about 0.1 weight percent to about 2 weight
percent each of said platinum and tin compounds, as metals, and
said weight percents are based on the total weight of the solid
component.
6. The carbonylation catalyst of claim 1 wherein said a vaporous
halogen promoting component is selected from the group consisting
of I.sub.2, Br.sub.2, and Cl.sub.2, hydrogen halides, gaseous
hydriodic acid, alkyl and aryl halides having up to 12 carbon
atoms, and mixtures thereof.
7. The carbonylation catalyst of claim 6 wherein said vaporous
halogen promoter is selected from the group consisting of hydrogen
iodide, methyl iodide, ethyl iodide, 1-iodopropane, 2-iodobutane,
1-iodobutane, hydrogen bromide, methyl bromide, ethyl bromide,
benzyl iodide and mixtures thereof.
8. The solid carbonylation catalyst of claim 1 wherein said
platinum compound is selected from the group consisting of a
platinum chloride, platinum oxide and mixtures thereof.
9. The scarbonylation catalyst of claim 1 wherein said platinum
compound is selected from the group consisting of dichlorodiammine
platinum; dichlorobis(triphenylphosphine)platinum;
dichloro(1,5-cyclooctadiene) platinum;
dichlorobis(benzonitrile)platinum, dihydrogen hexachloroplatinate
and mixtures thereof.
10. The carbonylation catalyst of claim 8 wherein said tin compound
is selected from the group consisting of tin (II) chloride, alkyl
carboxylate salts wherein at least one of the carbon atoms is bound
to tin and said alkyl group has from 1 to 10 carbon atoms, aryl
carboxylate salts wherein at least one of the carbon atoms is bound
to tin and said aryl group has from 6 to 24 carbon atoms, tin (II)
oxalate and mixtures thereof.
11. A carbonylation catalyst comprising a solid component
comprising from about 0.1 weight percent to about 10 weight percent
of a platinum compound, as metal, and from about 0.1 weight percent
to about 10 weight percent of a tin compound, as a metal,
associated with an activated carbon support material and a vaporous
component comprising a catalytically effective amount of a halogen
promoting component selected from the group consisting of hydrogen
iodide, methyl iodide, ethyl iodide, 1-iodopropane, 2-iodobutane,
1-iodobutane, hydrogen bromide, methyl bromide, ethyl bromide,
benzyl iodide and mixtures thereof, wherein said platinum and tin
compounds have a valency greater than zero and wherein said weight
percents are based on the total weight of the solid component.
12. The carbonylation catalyst of claim 11 wherein said solid
component has from about 0.1 weight percent to about 2 weight
percent each of said platinum and tin.
13. The carbonylation catalyst of claim 11 wherein said platinum
compound is selected from the group consisting of; dichlorodiammine
platinum; dichlorobis(triphenylphosphine)platinum;
dichloro(1,5-cyclooctadiene) platinum;
dichlorobis(benzonitrile)platinum, dihydrogen hexachloroplatinate
and mixtures thereof and said tin compound is selected from the
group consisting of tin (II) chloride, tin (II) oxalate and
mixtures thereof.
14. A carbonylation catalyst comprising a solid component
comprising from about 0.1 weight percent to about 2 weight percent
of platinum, as metal, the platinum being present as a platinum
selected from the group consisting of dichlorodiammine platinum;
dichlorobis(triphenylphosphine) platinum;
dichloro(1,5-cyclooctadiene)platinum;
dichlorobis(benzonitrile)platinum, dihydrogen hexachloroplatinate
and mixtures thereof, and from about 0.1 weight percent to percent
to about 2 weight percent of tin, as metal, the tin being present
as a tin compound selected from the group consisting of tin (II)
chloride, tin (II) oxalate and mixtures thereof which are
associated with an activated carbon support material, and a
vaporous component comprising at least one halide promoter selected
from the group consisting of hydrogen iodide, methyl iodide, ethyl
iodide, 1-iodopropane, 2-iodobutane, 1-iodobutane, hydrogen
bromide, methyl bromide, ethyl bromide, benzyl iodide and mixtures
thereof, and wherein said weight percents are based on the total
weight of the solid component.
15. A carbonylation catalyst comprising a solid component having
from about 0.1 weight percent to about 2 weight percent of a
platinum compound, as metal, and from about 0.1 weight percent to
about 2 weight percent of a tin compound, as metal, associated with
an activated carbon support material and a vaporous component
comprising a catalytically effective amount of a halogen promoting
component selected from the group consisting of hydrogen iodide,
methyl iodide, ethyl iodide, 1-iodopropane, 2-iodobutane,
1-iodobutane, hydrogen bromide, methyl bromide, ethyl bromide,
benzyl iodide and mixtures thereof, wherein said platinum and tin
compounds have a valency greater than zero and wherein said weight
persents are based on the total weight of the solid component.
16. The carbonylation catalyst of claim 15 wherein said platinum
compound is selected from the group consisting of, dichlorodiammine
platinum; dichlorobis(triphenylphosphine)platinum;
dichloro(1,5-cyclooctadiene) platinum;
dichlorobis(benzonitrile)platinum, dihydrogen hexachloroplatinate
and mixtures thereof and said tin component is selected from the
group consisting of tin (II) chloride, tin (II) oxalate and
mixtures thereof.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a carbonylation catalyst, and
specifically, to a vapor-phase carbonylation catalyst having
platinum and tin associated with a solid support material. More
particularly, the present invention relates to a vapor-phase
carbonylation catalyst having a solid-phase component which
includes platinum and tin associated with a solid support material
and at least one vaporous halide promoter component. The
carbonylation catalyst is particularly useful for the production of
acetic acid, methyl acetate and mixtures thereof from methanol,
dimethyl ether and methyl ester and ester-alcohol mixtures.
Lower carboxylic acids and esters such as acetic acid and methyl
acetate have been known as industrial chemicals for many years.
Acetic acid is used in the manufacture of a variety of intermediary
and end-products. For example, an important derivative is vinyl
acetate which can be used as monomer or co-monomer for a variety of
polymers. Acetic acid itself is used as a solvent in the production
of terephthalic acid, which is widely used in the container
industry, and particularly in the formation of PET beverage
containers.
There has been considerable research activity in the use of metal
catalysts for the carbonylation of lower alkyl alcohols, such as
methanol, and ethers to their corresponding carboxylic acids and
esters, as illustrated in equations 1-3 below:
Carbonylation of methanol is a well known reaction and is typically
carried out in the liquid phase with a catalyst. A thorough review
of these commercial processes and other approaches to accomplishing
the formation of acetyl from a single carbon source is described by
Howard et al. in Catalysis Today, 18, 325-354 (1993). Generally,
the liquid phase carbonylation reactions for the preparation of
acetic acid using methanol are performed using homogeneous catalyst
systems comprising a Group VIII metal and a halogen component such
as iodine or bromine or an iodine or bromine-containing compound
such as hydrogen iodide, hydrogen bromide, methyl iodide, or methyl
bromide. Rhodium is the most common Group VIII metal catalyst and
methyl iodide is the most common promoter. These reactions are
conducted in the presence of water to prevent precipitation of the
catalyst.
These recently developed processes represent a distinct improvement
over the classic carbonylation processes wherein such feed
materials have been previously carbonylated in the presence of such
catalyst systems as phosphoric acid, phosphates, activated carbon,
heavy metal salts and metal carbonyls such as cobalt carbonyl, iron
carbonyl and nickel carbonyl. All of these previously known
processes require the use of extremely high partial pressures of
carbon monoxide. They also have the disadvantage of requiring
higher catalyst concentrations, longer reaction times, and higher
temperatures to obtain substantial reaction and conversion rates.
This results in needing larger and more costly processing equipment
and higher manufacturing costs.
A disadvantage of a homogeneous phase carbonylation process is that
additional steps are necessary for separating the products from the
catalyst solutions, and there are always handling losses of the
catalyst. Losses of the metal in the catalyst can be attributed to
several factors, such as the plating-out of the active metal onto
piping and process equipment thereby rendering the metal inactive
for carbonylation purposes and losses due to incomplete separation
of the catalyst from the products. These losses of the metal
component are costly because the metals themselves are very
expensive.
Schultz, in U.S. Pat. No. 3,689,533, discloses using a supported
rhodium catalyst for the carbonylation of alcohols to form
carboxylic acids in a vapor-phase reaction. Schultz further
discloses the presence of a halide promoter.
Schultz in U.S. Pat. No. 3,717,670 describes a similar supported
rhodium catalyst in combination with promoters selected from Groups
IB, IIIB, IVB, VB, VIB, VIII, lanthanide and actinide elements of
the Periodic Table.
Uhm, in U.S. Pat. No. 5,488,143, describes the use of alkali,
alkaline earth or transition metals as promoters for supported
rhodium for the halide-promoted, vapor phase methanol carbonylation
reaction. Pimblett, in U.S. Pat. No. 5,258,549, teaches that the
combination of rhodium and nickel on a carbon support is more
active than either metal by itself.
In addition to the use of iridium as a homogeneous alcohol
carbonylation catalyst, Paulik et al., in U.S. Pat. No. 3,772,380,
describe the use of iridium on an inert support as a catalyst in
the vapor phase, halogen-promoted, heterogeneous alcohol
carbonylation process.
European Patent Application EP 0 759 419 A1 pertains to a process
for the carbonylation of an alcohol and/or a reactive derivative
thereof. EP 0 759 419 A1 discloses a carbonylation process
comprising a first carbonylation reactor wherein an alcohol is
carbonylated in the liquid phase in the presence of a homogeneous
catalyst system and the off gas from this first reactor is then
mixed with additional alcohol and fed to a second reactor
containing a supported catalyst. The homogeneous catalyst system
utilized in the first reactor comprises a halogen component and a
Group VIII metal selected from rhodium and iridium. When the Group
VIII metal is iridium, the homogeneous catalyst system also may
contain an optional co-promoter selected from the group consisting
of ruthenium, osmium, rhenium, cadmium, mercury, zinc, indium and
gallium. The supported catalyst employed in the second reactor
comprises a Group VIII metal selected from the group consisting of
iridium, rhodium, and nickel, and an optional metal promoter on a
carbon support. The optional metal promoter may be iron, nickel,
lithium and cobalt. The conditions within the second carbonylation
reactor zone are such that mixed vapor and liquid phases are
present in the second reactor. The presence of a liquid phase
component in the second reactor inevitably leads to leaching of the
active metals from the supported catalyst which, in turn, results
in a substantial decrease in the activity of the catalyst and
costly replacement of the active catalyst component.
The literature contains several reports of the use of
rhodium-containing zeolites as vapor phase alcohol carbonylation
catalysts at one bar pressure in the presence of halide promoters.
The lead references on this type of catalyst are presented by
Maneck et al. in Catalysis Today, 3, 421-429 (1988). Gelin et al.,
in Pure & Appl. Chem., Vol. 60, No. 8, 1315-1320 (1988),
provide examples of the use of rhodium or iridium contained in
zeolite as catalysts for the vapor phase carbonylation of methanol
in the presence of halide promoter. Krzywicki et al., in Journal of
Molecular Catalysis, 6, 431-440 (1979), describe the use of silica,
alumina, silica-alumina and titanium dioxide as supports for
rhodium in the halide-promoted vapor phase carbonylation of
methanol, but these supports are generally not as efficient as
carbon. Luft et al., in U.S. Pat. No. 4,776,987 and in related
disclosures, describe the use of chelating ligands chemically
attached to various supports as a means to attach Group VIII metals
to a heterogeneous catalyst for the halide-promoted vapor phase
carbonylation of ethers or esters to carboxylic anhydrides.
Evans et al., in U.S. Pat. No. 5,185,462, describe heterogeneous
catalysts for halide-promoted vapor phase methanol carbonylation
based on noble metals attached to nitrogen or phosphorus ligands
attached to an oxide support.
Panster et al., in U.S. Pat. No. 4,845,163, describe the use of
rhodium-containing organopolysiloxane-ammonium compounds as
heterogeneous catalysts for the halide-promoted liquid phase
carbonylation of alcohols.
Drago et al., in U.S. Pat. No. 4,417,077, describe the use of anion
exchange resins bonded to anionic forms of a single transition
metal as catalysts for a number of carbonylation reactions
including the halide-promoted carbonylation of methanol. Although
supported ligands and anion exchange resins may be of some use for
immobilizing metals in liquid phase carbonylation reactions, in
general, the use of supported ligands and anion exchange resins
offer no advantage in the vapor phase carbonylation of alcohols
compared to the use of the carbon as a support for the active metal
component. Moreover, these catalysts are typically unstable at
elevated temperatures making them poorly suited to a vapor phase
process.
Nickel on activated carbon has been studied as a heterogeneous
catalyst for the halide-promoted vapor phase carbonylation of
methanol. Relevant references to the nickel-on-carbon catalyst
systems are provided by Fujimoto et al. in Chemistry Letters
895-898, (1987). Moreover, Fujimoto et al. in Journal of Catalysis,
133, 370-382 (1992) observed increased rates when hydrogen is added
to the feed mixture. Liu et al., in Ind. Eng. Chem. Res., 33
488-492, (1994), report that tin enhances the activity of the
nickel-on-carbon catalyst. Mueller et al., in U.S. Pat. No.
4,918,218, disclose the addition of palladium and optionally copper
to supported nickel catalysts for the halide-promoted carbonylation
of methanol. In general the rates of reaction provided by
nickel-based catalysts are lower than those provided by the
analogous rhodium-based catalysts when operated under similar
conditions.
Other single metals supported on carbon have been reported by
Fujimoto et al. in Catalysis Letters, 2, 145-148 (1989) to have
limited activity in the halide-promoted vapor phase carbonylation
of methanol. The most active of these metals is Sn. Following Sn in
order of decreasing activity are Pb, Mn, Mo, Cu, Cd, Cr, Re, V, Se,
W, Ge and Ga. None of these other single metal catalysts are nearly
as active as those based on Rh, Ir, Ni or the catalyst of the
present invention.
Yagita and Fujimoto in Journal of Molecular Catalysis, 69, 191-197
(1991) examined the role of activated carbon in a metal supported
catalyst and observed that the carbonylation activities of Group
VIII metals supported on activated carbon are ordered by the
affinities between the metal and the halogen.
Feitler, in U.S. Pat. No. 4,612,387, describes the use of certain
zeolites containing no transition metals as catalysts for the
halide-free carbonylation of alcohols and other compounds in the
vapor phase.
U.S. Pat. No. 5,218,140, describes a vapor phase process for
converting alcohols and ethers to carboxylic acids and esters by
the carbonylation of alcohols and ethers with carbon monoxide in
the presence of a metal ion exchanged heteropoly acid supported on
an inert support. The catalyst used in the reaction includes a
polyoxometallate anion in which the metal is at least one of a
Group V(a) and VI(a) is complexed with at least one Group VIII
cation such as Fe, Ru, Os, Co, Rh, Ir, Ni, Pd or Pt as catalysts
for the halide-free carbonylation of alcohols and other compounds
in the vapor phase.
In accordance with the present invention, a platinum and tin solid
supported catalyst is provided for heterogeneous vapor-phase
carbonylation of reactants comprising lower alkyl alcohols, ether
and ester derivatives of the alcohols, and mixtures of
ester-alcohols for producing esters and carboxylic acids.
Surprisingly, the platinum and tin catalyst demonstrate significant
rate improvements when compared to catalysts containing platinum as
the sole active metal.
SUMMARY OF THE INVENTION
Briefly, the present invention provides a catalyst useful for the
vapor-phase carbonylation of lower alkyl alcohols, lower alkyl
alcohol generating compositions such as ether and ester derivatives
of the alcohols, and mixtures thereof for producing esters and
carboxylic acids. The catalyst includes a first component
comprising platinum and/or platinum salt and tin and/or tin salt
which are associated with a solid support material and a vaporous
component comprising a halide promoter. As used herein the term
"associated with" includes any manner that permits the platinum
metal and/or its salt and the tin metal and/or its salt to reside
on or in the solid support. Non-limiting examples in which the
platinum and tin metals or their respective salts may be associated
with the solid support include impregnating, immersing, spraying,
and coating the support with a solution containing platinum and
with a solution containing tin sequentially or impregnating,
immersing, spraying, and coating the support with a solution
containing a mixture of platinum and tin.
It is an object of the present invention to provide a catalyst
useful in a vapor-phase carbonylation process. It is another object
of the invention to provide a vapor-phase carbonylation catalyst
having platinum or platinum salt and tin or tin salt associated
with a solid support material and a vaporous halide promoter
component.
These and other objects and advantages of the invention will become
apparent to those skilled in the art from the accompanying detailed
description.
DETAILED DESCRIPTION OF THE INVENTION
The catalyst of the present invention is particularly useful for
the continuous production of carboxylic acids and esters by
reacting lower alkyl alcohols, lower alkyl alcohol generating
compositions such as ether and ester derivatives of the alcohols,
and mixtures thereof in a vapor-phase carbonylation process. In
accordance with the invention, the catalyst has a solid state
component which includes platinum and/or platinum salt and tin
and/or tin salt associated with a solid support material and a
vaporous halide promoter component. Desirably, the support material
is inert to the carbonylation reaction. In a preferred embodiment,
the catalyst is particularly useful for vapor-phase carbonylation
for producing acetic acid, methyl acetate and mixtures thereof from
methanol and its derivatives. Desirably, the vapor-phase
carbonylation process is operated at temperatures above the dew
point of the reactants and products, i.e., the temperature at which
condensation occurs. However, since the dew point is a complex
function of dilution (particularly with respect to non-condensable
gases such as unreacted carbon monoxide, hydrogen, or inert diluent
gas), product composition, and pressure, the process may still be
operated over a wide range of temperatures, provided the
temperature exceeds the dew point of the reactants and products. In
practice, this generally dictates a temperature range of about
100.degree. C. to about 500.degree. C., with temperatures of about
100.degree. C. to about 350.degree. C. being preferred and
temperatures of about 150.degree. C. to 275.degree. C. being
particularly useful.
As with temperature, the useful pressure range is limited by the
dew point of the product mixture. Provided that the reaction is
operated at a temperature sufficient to prevent liquefaction of the
reactants and products, a wide range of pressures may be used,
e.g., pressures in the range of about 0.1 to 100 bars absolute. The
process preferably is carried out at a pressure in the range of
about 1 to 50 bars absolute, most preferably, about 3 to 30 bar
absolute (bara).
Suitable feedstock, i.e., reactants, for carbonylation using the
catalyst of the present invention include lower alkyl alcohols,
lower alkyl alcohol generating compositions, such as ether and
ester derivatives of the alcohols, and mixtures thereof.
Non-limiting examples of reactants include alcohols and ethers in
which an aliphatic carbon atom is directly bonded to an oxygen atom
of either an alcoholic hydroxyl group in the compound or an ether
oxygen in the compound and may further include aromatic moieties.
Preferably, the feedstock is one or more lower alkyl alcohols
having from 1 to 10 carbon atoms and preferably having from 1 to 6
carbon atoms, alkane polyols having 2 to 6 carbon atoms, alkyl
alkylene polyethers having 3 to 20 carbon atoms and alkoxyalkanols
having from 3 to 10 carbon atoms. The most preferred reactant is
methanol. Although methanol is preferably used in the process and
is normally fed as methanol, it can be supplied in the form of a
combination of materials which generate methanol. Examples of such
combination of materials include (i) methyl acetate and water and
(ii) dimethyl ether and water. In the operation of the process,
both methyl acetate and dimethyl ether are formed within the
reactor and, unless methyl acetate is the desired product, they are
recycled with water to the reactor where they are later consumed to
form acetic acid. Accordingly, one skilled in the art will further
recognize that it is possible to utilize the catalyst of the
present invention produce a carboxylic acid from an ester feed
material.
Although the presence of water in the gaseous feed mixture is not
essential when using methanol, the presence of some water is
desirable to suppress formation of methyl acetate and/or dimethyl
ether. When using methanol to generate acetic acid, the molar ratio
of water to methanol can be 0:1 to 10:1, but preferably is in the
range of 0.01:1 to 1:1. When using an alternative source of
methanol such as methyl acetate or dimethyl ether, the amount of
water fed usually is increased to account for the mole of water
required for hydrolysis of the methanol alternative. Accordingly,
when using either methyl acetate or dimethyl ether, the mole ratio
of water to ester or ether is in the range of 1:1 to 10:1, but
preferably in the range of 1:1 to 3:1. In the preparation of acetic
acid, it is apparent that combinations of methanol, methyl ester,
and/or dimethyl ether are equivalent, provided the appropriate
amount of water is added to hydrolyze the ether or ester to provide
the methanol reactant.
When the methyl ester, methyl acetate, is the desired product, no
water should be added to the carbonylation process and dimethyl
ether becomes the preferred feedstock. Further, when methanol is
used as the feedstock in the preparation of methyl acetate, it is
necessary to remove water. However, the primary utility of the
process of the present invention is in the manufacture of acetic
acid.
In the practice of a vapor-phase carbonylation process, the
reactant, in the vapor phase, is passed through or over the solid
phase component of the catalyst of the present invention along with
the vapor phase halide promoter component of the invention
catalyst. The solid phase component of the catalyst includes
platinum and tin associated with a substantially inert solid
support material.
The form of platinum used to prepare the catalyst generally is not
critical. The solid phase component of the catalyst may be prepared
from a wide variety of platinum containing compounds and can be in
the form of a salt of a mineral acid halide, such as chloroplatinic
acid; trivalent nitrogen compounds such as dichlorodiammine
platinum; organic compounds of trivalent phosphorous, such as
dichlorobis(triphenylphosphine)platinum; olefins, such as
dichloro(1,5-cyclooctadiene) platinum; nitriles, such as
dichlorobis(benzonitrile)platinum and oxides of platinum may be
used if dissolved in the appropriate medium either alone or in
combination. The preferred sources of platinum is one of it
chlorides, such as any of the various salts of
hexachloroplatinate(IV) or a solution of platinum dichloride in
either aqueous HCl or aqueous ammonia.
The amount of platinum, as metal, on the support can vary from
about 0.01 weight percent to about 10 weight percent, with from
about 0.1 weight percent to about 2 weight percent platinum being
preferred based on the total weight of the solid supported
catalyst.
The form of tin used to prepare the catalyst generally is not
critical. The solid phase component of the catalyst may be prepared
from a wide variety of tin containing compounds. Suitable tin
compounds include tin halides such as tin (II) chloride; alkyl
carboxylate salts and aryl carboxylate salts wherein the alkyl
group has from 1 to 10 carbon atoms and the aryl group has from 6
to 24 carbon atoms wherein at least one of the carbon atoms is
bound to the tin moiety, tin oxides such as tin (II) oxalate, and
mixtures of such tin containing compounds. The preferred sources of
tin materials for use in this invention, based on their
availability, cost, lower toxicity, and high solubility in water
(the preferred solvent medium) are tin (II) chloride, preferably
dissolved in aqueous HCl, and tin (II) oxalate.
The content of tin, as metal, on the support can vary over a wide
range, for example from about 0.01 to 10 weight percent tin based
on the total weight of the solid supported catalyst. However, the
preferred amount of tin in the catalyst is from about 0.1 to 5
weight percent of tin based on the total weight of the solid
supported catalyst.
Another advantage of the present invention is that platinum and tin
are less volatile and less soluble when compared to other active
catalysts, such as Ir and Rh, and therefore are less likely to be
removed from the catalyst support during operation of the
carbonylation process. Surprisingly, the combination of platinum
and tin demonstrate catalytic activity for vapor-phase
carbonylation of lower alkyl alcohols, ether derivatives of the
alcohols, ester derivatives of the alcohols, and ester-alcohol
mixtures for producing esters and carboxylic acids without the
presence of rhodium.
The solid support useful for acting as a carrier for the platinum
and tin consists of a porous solid of such size that it can be
employed in fixed or fluidized bed reactors. Typical support
materials have a size of from about 400 mesh per inch to about 1/2
inch. Preferably, the support is carbon, including activated
carbon, having a high surface area. Activated carbon is well known
in the art and may be derived from coal or peat having a density of
from about 0.03 grams/cubic centimeter (g/cm.sup.3) to about 2.25
g/cm.sup.3. The carbon can have a surface area of from about 200
square meters/gram (m.sup.2 /g) to about 1200 m.sup.2 /g. Other
solid support materials, which may be used in accordance with the
present invention, include pumice, alumina, silica, silica-alumina,
magnesia, diatomaceous earth, bauxite, titania, zirconia, clays,
magnesium silicate, silicon carbide, zeolites, and ceramics. The
shape of the solid support is not particularly important and can be
regular or irregular and include extrudates, rods, balls, broken
pieces and the like disposed within the reactor.
The platinum and tin can be associated with the solid support by
solubilizing the metals, or their respective salts, in a suitable
solvent and contacting the solubilized platinum and tin with the
solid support material. The solvent is then evaporated so that at
least a portion of the platinum and tin is associated with the
solid support. Drying temperatures can range from about 100.degree.
C. to about 600.degree. C. for a period greater than about one
second. One skilled in the art will understand that the drying time
is dependent upon the temperature, humidity, and solvent.
Generally, lower temperatures require longer heating periods to
effectively evaporate the solvent from the solid support. The
method of preparing the solid component of the catalyst optionally
further includes the step of heating the solid supported platinum
and tin in a stream of inert gas. Non-limiting examples of suitable
inert gases include nitrogen, argon and helium
Alternatively the platinum and tin can be associated with the solid
support by sequentially associating each metal with a support
material. For example, platinum or a platinum containing salt would
be solubilized using a suitable solvent. The dissolved metal
solution would then be contacted with the support material.
Afterwards, the solvent is evaporated so that at least a portion of
the platinum is associated with the solid support material. Next,
tin or a tin containing salt would be associated with the support
material following a similar procedure as described for associating
the platinum with the solid carrier. Thus, one will understand that
multiple layers of the respective platinum and tin metals or metal
containing compounds can be associated with the support by merely
following multiple steps of the procedure described above.
The catalyst system further includes a vaporous halide promoter
selected from chlorine, bromine and iodine compounds. Preferably,
the vaporous halide is selected from bromine and iodine compounds
that are vaporous under vapor-phase carbonylation conditions of
temperature and pressure. Suitable halides include hydrogen halides
such as hydrogen iodide and gaseous hydriodic acid; alkyl and aryl
halides having up to 12 carbon atoms such as, methyl iodide, ethyl
iodide, 1-iodopropane, 2-iodobutane, 1-iodobutane, methyl bromide,
ethyl bromide, benzyl iodide and mixtures thereof. Desirably, the
halide is a hydrogen halide or an alkyl halide having up to 6
carbon atoms. Non-limiting examples of preferred halides include
hydrogen iodide, methyl iodide, hydrogen bromide, methyl bromide
and mixtures thereof. The halide may also be a molecular halide
such as I.sub.2, Br.sub.2, or Cl.sub.2.
The molar ratio of methanol or methanol equivalents to halide
present to produce an effective carbonylation ranges from about 1:1
to 10,000:1, with the preferred range being from about 5:1 to about
1000:1.
In a preferred aspect of the invention, the vapor-phase
carbonylation catalyst of the present invention may be used for
making acetic acid, methyl acetate or a mixture thereof. The
process includes the steps of contacting a gaseous mixture
comprising methanol and carbon monoxide with a catalyst system in a
carbonylation zone and recovering a gaseous product from the
carbonylation zone. The catalyst system includes a solid-phase
component comprising platinum and tin deposited on a carbon support
and a vapor-phase component comprising at least one halide promoter
described above.
The carbon monoxide may be fed to the carbonylation zone either as
purified carbon monoxide or as a mixture of hydrogen and carbon
monoxide. Although hydrogen is not part of the reaction
stoichiometry, hydrogen may be useful in maintaining optimal
catalyst activity. The preferred ratio of carbon monoxide to
hydrogen generally ranges from about 99:1 to about 2:1, but ranges
with even higher hydrogen levels may be useful.
The present invention is illustrated in greater detail by the
specific examples present below. It is to be understood that these
examples are illustrative embodiments and are not intended to be
limiting of the invention, but rather are to be construed broadly
within the scope and content of the appended claims.
EXAMPLES
Catalyst 1
In preparation the catalyst, 579 mg of dihydrogen
hexachloroplatinate having an assay of 39.23% (1.17 mmol of Pt) was
dissolved in 30 mL of distilled water. This solution was added to
20.0 grams of 12.times.40 mesh activated carbon granules contained
in an evaporating dish. The activated carbon granules had a BET
surface area in excess of 800 m.sup.2 /g. This mixture was heated
using a steam bath and continuously stirred until the support
granules became free flowing. The impregnated catalyst was then
transferred to a quartz tube measuring 106 cm long by 25 mm outer
diameter. The quartz tube was thereafter placed in a three-element
electric tube furnace so that the mixture was located in the
approximate center of the 61 cm long heated zone of the furnace.
Nitrogen was continuously passed through the catalyst bed at a rate
of 100 standard cubic centimeters per minute. The tube was heated
from ambient temperature to 300.degree. C. over a 2 hour period,
held at 300.degree. C. for 2 hours and then allowed to cool back to
ambient temperature.
To the catalyst prepared above was added a solution having 0.263
grams (1.17 mmol) of tin (II) chloride dihydrate dissolved in a
mixture of 10 mL of 11.6 M HCl and 20 mL of distilled water. The
catalyst mixture was heated again using the steam bath and
continuously stirring until the granules became free flowing. The
impregnated catalyst was then transferred to a quartz tube
measuring 106 cm long by 25 mm outer diameter. The quartz tube
containing the mixture was placed in a three-element electric tube
furnace so that the mixture was located in the approximate center
of the 61 cm long heated zone of the furnace. Nitrogen was
continuously passed through the catalyst bed at a rate of 100
standard cubic centimeters per minute. The tube was heated from
ambient temperature to 300.degree. C. over a 2 hour period, held at
300.degree. C. for 2 hours and then allowed to cool back to ambient
temperature.
The solid supported catalyst in accordance with the present
invention, (Catalyst I) contained 1.09% Pt, 0.66% Sn, and had a
density of 0.57 g per mL.
Comparative Catalyst Example I
In preparing a comparative catalyst containing only platinum as the
active metal, 569 mg of dihydrogen hexachloroplatinate having a Pt
assay of 40%, (1.17 mmol of Pt) was dissolved in 30 mL of distilled
water. This solution was added to 20.0 g of 12.times.40 mesh
activated carbon granules contained in an evaporating dish. The
activated carbon granules had a BET surface area in excess of 800
m.sup.2 /g. This mixture was heated using a steam bath and
continuously stirred until the support granules became free
flowing. The impregnated catalyst was then transferred to a quartz
tube measuring 106 cm long by 25 mm outer diameter. The quartz tube
was thereafter placed in a three-element electric tube furnace so
that the mixture was located in the approximate center of the 61 cm
long heated zone of the furnace. Nitrogen was continuously passed
through the catalyst bed at a rate of 100 standard cubic
centimeters per minute. The tube was heated from ambient
temperature to 300.degree. C. over a 2 hour period, held at
300.degree. C. for 2 hours and then allowed to cool back to ambient
temperature.
The catalyst (Comparative Catalyst C-I) contained 1.10% Pt and had
a density of 0.57 g per mL.
Comparative Catalyst Example II
A second comparative catalyst was prepared by dissolving 0.29 grams
of nickelous acetate tetrahydrate (1.17 mmol) and 0.263 grams (1.17
mmol) of tin (II) chloride dihydrate in a solution consisting of 20
mL of distilled water and 10 mL of 11.6 M HCl. The solution was
then added to 20.0 g of 12.times.40 mesh activated carbon granules
contained in an evaporating dish. The activated carbon granules had
a BET surface area in excess of 800 m.sup.2 /g. The impregnated
catalyst was then transferred to a quartz tube measuring 106 cm
long by 25 mm outer diameter. The quartz tube was thereafter placed
in a three-element electric tube furnace so that the mixture was
located in the approximate center of the 61 cm long heated zone of
the furnace. Nitrogen was continuously passed through the catalyst
bed at a rate of 100 standard cubic centimeters per minute. The
tube was heated from ambient temperature to 300.degree. C. over a
2-hour period, held at 300.degree. C. for 2 hours and then allowed
to cool back to ambient temperature.
The catalyst (Comparative Catalyst C-II) contained 0.33% Ni, 0.67%
Sn, and had a density of 0.57 g per mL.
Comparative Catalyst Example III
A third comparative catalyst was prepared by dissolving 0.207 grams
(1.17 mmol) of palladium chloride in 10 mL of 11.6 M HCl. In a
separate vessel, 0.263 grams of tin (II) chloride dihydrate were
dissolved in 10 mL of 11.6 M HCl. Both solutions were combined and
mixed until uniform and the solution of dissolved palladium and tin
was diluted with 10 mL of distilled water. The solution was then
added to 20.0 g of 12.times.40 mesh activated carbon granules
contained in an evaporating dish. The activated carbon granules had
a BET surface area in excess of 800 m.sup.2 /g. The impregnated
activated carbon granules were then dried using the procedure
described above.
The catalyst (Comparative Catalyst C-III) contained 0.61% Pd, 0.68%
Sn, and had a density of 0.57 g per mL.
Comparative Catalyst Example IV
A fourth comparative catalyst was prepared using the procedure
described above to prepare the platinum catalyst in Comparative
Catalyst Example I, except 418 mg (1.17 mmol) of iridium
trichloride hydrate were used in place of the dihydrogen
hexachloroplatinate. The catalyst (Comparative Catalyst C-IV)
contained 1.10% Ir.
Carbonylation of Methanol
The reactor system consisted of a 800 to 950 mm (31.5 and 37 inch)
section of 6.35 mm (1/4 inch) diameter tubing constructed of
Hastelloy C alloy. The upper portion of the tube constituted the
preheater and reaction (carbonylation) zones. These zones were
assembled by inserting a quartz wool pad 410 mm from the top of the
reactor to act as support for the catalyst, followed sequentially
by: (1) a 0.7 g bed of fine quartz chips (840 microns); (2) 0.5 g
of one of the catalysts prepared as described in the preceding
examples; and (3) an additional 6 g of fine quartz chips. The top
of the tube was attached to an inlet manifold for introducing
liquid and gaseous feeds.
The six grams of fine quartz chips acted as a heat exchange surface
to vaporize the liquid feeds. Care was taken not to allow any of
the liquid feeds to contact the catalyst bed at any time, including
assembly, start-up, operation, and shutdown. The remaining lower
length of tubing (product recovery section) consisted of a vortex
cooler which varied in length depending on the original length of
tubing employed and was maintained at approximately 0-5.degree. C.
during operation.
The gases were fed using Brooks flow controllers and liquids were
fed using a high performance liquid chromatography pump. The
gaseous products leaving the reaction zone were condensed using a
vortex cooler operating at 0-5.degree. C. The product reservoir was
a tank placed downstream from the reactor system. The pressure was
maintained using a modified Research control valve on the outlet
side of the reactor system and the temperature of the reaction
section was maintained using heating tape on the outside of the
reaction system.
Feeding of hydrogen and carbon monoxide to the reactor was
commenced while maintaining the reactor at a temperature of
240.degree. C. and a pressure of 17.2 bara (250 psia). The flow
rate of hydrogen was set at 25 standard cc/min and the carbon
monoxide flow rate was set at 100 cc/min. The reactor section was
maintained under these conditions for 1 hour or until the
temperature and pressure had stabilized, whichever was longer. The
high pressure liquid chromatography pump was then started, feeding
a mixture consisting of 70 weight percent methanol and 30 weight
percent methyl iodide at a rate of 10-12 g per hour. Samples of the
liquid product were collected and analyzed periodically using gas
chromatographic techniques.
Carbonylation Example 1
The composition and weight of the samples taken periodically during
the procedure described above in which Catalyst I was used are set
forth in Table I. "Time" is the total time of carbonylation (in
hours) commencing with the feeding of the methanol until a
particular sample was taken. In the tables "MeI" is the weight
percentage of methyl iodide present in the sample, "MeOAc" is the
weight percentage of methyl acetate present in the sample, "MeOH"
is the weight percentage of methanol present in the sample and
"HOAc" the weight percentage of acetic acid present in the sample.
The weight of each sample is given in grams.
TABLE I Sample Expired MeOH Sample Number Time (h) MeI MeOAc (Wt.
%) HOAc Weight (g) 1 3.00 15.01 6.25 72.06 0.1 45.9 2 5.00 14.83
6.12 70.43 0.1 29.6 3 10.50 16.55 16.31 58.29 0.46 72.1 4 12.50
17.12 16.95 60.78 0.48 28.9 5 18.00 16.64 16.5 58.98 0.48 81.5 6
20.00 13.62 39.28 15.47 15.76 28.7 7 22.00 13.42 39.7 15.82 16.19
29 8 24.00 13.57 39.63 15.78 16.12 28.5 9 26.00 15.1 39.23 18.91
12.06 28.9 10 29.00 15.21 40.19 18.53 11.4 29.1 11 34.00 16 38.72
13.03 17.44 80.1 12 36.50 15.86 39.26 13.24 17.7 24.1 13 42.00
15.98 38.47 13.06 17.56 81.5 14 44.00 15.59 39.49 10.26 20.55 24.8
15 46.00 15.69 39.51 10.27 20.55 24.5
The rate of acetyl production based on the preceding experiment
utilizing Catalyst I is set forth in Table II wherein Sample Number
and Time values correspond to those of Table I. "Acetyl Produced"
is the amount (millimoles) of methyl acetate and acetic acid
produced during each increment of Time calculated from the
formula:
"Production Rate" is the moles of Acetyl Produced per liter of
catalyst volume per hour during each increment of Time (Time
Increment), i.e., the time of operation between samples. The
formula for determining moles of Acetyl Produced per liter of
catalyst volume per hour is:
wherein 0.5 is the grams of catalyst used and 0.57 is the density
of the catalyst in g/mL.
TABLE II Acetyl Sample Number Expired Time (h) Produced (mmol) Rate
(mol/L-h) 1 3.00 39.5 15.0 2 5.00 25.0 14.2 3 10.50 164.4 34.1 4
12.50 68.5 39.0 5 18.00 188.2 39.0 6 20.00 227.7 129.8 7 22.00
233.8 133.3 8 24.00 229.2 130.6 9 26.00 211.3 120.4 10 29.00 213.3
81.1 11 34.00 651.9 148.6 12 36.50 199.0 90.7 13 42.00 662.2 137.3
14 44.00 217.3 123.9 15 46.00 214.7 122.4
Over 46 hours of testing, the catalyst produced 3.55 moles of
acetyl. This represents a rate of 154 moles of acetyl/kg.sub.cat -h
or, represented as an hourly space velocity, 88 mol of
acetyl/L.sub.cat -h.
Comparative Carbonylation Examples
Comparative Catalysts C-I-C-IV, were utilized in the carbonylation
of methanol according to the above-described procedure. The
Production Rate, expressed in terms of moles of Acetyl Produced per
kilogram of catalyst per hour and moles per liter of catalyst
volume per hour, for each of Catalyst I and Comparative Catalysts
C-I-C-IV, are shown in Table III. As can be seen from Table III,
the catalyst in accordance with the present invention is
significantly more active than a catalyst using Pt as the sole
active metal. Further, when compared to tin promoted catalysts for
the other members of the triad, platinum is far superior to either
nickel or palladium. Comparative Example C-4 shows that
carbonylation rates using the catalyst of the present invention are
superior to those obtained using iridium alone on an activated
carbon support.
TABLE III Carbonylation Production Rate Example Catalyst in
moles/kg.sub.cat -h in moles/L.sub.cat -h 1 I 154 88 (Pt-Sn) C-1
C-I 89 45 (Pt) C-2 C-II 6 3 (Ni-Sn) C-3 C-III 19 11 (Pd-Sn) C-4
C-IV 93 53 (Ir)
Having described the invention in detail, those skilled in the art
will appreciate that modifications may be made to the various
aspects of the invention without departing from the scope and
spirit of the invention disclosed and described herein. It is,
therefore, not intended that the scope of the invention be limited
to the specific embodiments illustrated and described but rather it
is intended that the scope of the present invention be determined
by the appended claims and their equivalents. Moreover, all
patents, patent applications, publications, and literature
references presented herein are incorporated by reference in their
entirety for any disclosure pertinent to the practice of this
invention.
* * * * *